Recipe for Salmon with Lime and Watercress Sauce

4 salmon steaks (150-175g)
1 lime, zest and juice
1 bunch watercress
300 g Greek-style yogurt

Put the salmon steaks into a frying pan and add cold water to cover
halfway up their sides. Add the lime juice. Heat gently until
almost boiling then turn off the heat. Turn the salmon steaks over
and let them cool in the water for about 15-20 minutes when they
will be cooked. Check that the flesh flakes easily and looks
opaque. Reserve a few sprigs of the watercress for garnish then
blend the remainder with the yoghurt and lime zest in a blender or
food processor. Season to taste. Serve the salmon with the sauce